/* kitty: C++ truth table library
 * Copyright (C) 2017-2019  EPFL
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use,
 * copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following
 * conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 */

/*!
  \file algorithm.hpp
  \brief Implements several generic algorithms on truth tables

  \author Mathias Soeken
*/

#pragma once

#include <algorithm>
#include <cassert>

#include "bit_operations.hpp"
#include "detail/constants.hpp"
#include "static_truth_table.hpp"

namespace kitty
{

/*! \brief Perform bitwise unary operation on truth table

  \param tt Truth table
  \param op Unary operation that takes as input a word (`uint64_t`) and returns a word

  \return new constructed truth table of same type and dimensions
 */
template<typename TT, typename Fn>
auto unary_operation( const TT& tt, Fn&& op )
{
  auto result = tt.construct();
  std::transform( tt.cbegin(), tt.cend(), result.begin(), op );
  result.mask_bits();
  return result;
}

/*! \cond PRIVATE */
template<int NumVars, typename Fn>
auto unary_operation( const static_truth_table<NumVars, true>& tt, Fn&& op )
{
  auto result = tt.construct();
  result._bits = op( tt._bits );
  result.mask_bits();
  return result;
}
/*! \endcond */

/*! \brief Perform bitwise binary operation on two truth tables

  The dimensions of `first` and `second` must match.  This is ensured
  at compile-time for static truth tables, but at run-time for dynamic
  truth tables.

  \param first First truth table
  \param second Second truth table
  \param op Binary operation that takes as input two words (`uint64_t`) and returns a word

  \return new constructed truth table of same type and dimensions
 */
template<typename TT, typename Fn>
auto binary_operation( const TT& first, const TT& second, Fn&& op )
{
  assert( first.num_vars() == second.num_vars() );

  auto result = first.construct();
  std::transform( first.cbegin(), first.cend(), second.cbegin(), result.begin(), op );
  result.mask_bits();
  return result;
}

/*! \cond PRIVATE */
template<int NumVars, typename Fn>
auto binary_operation( const static_truth_table<NumVars, true>& first, const static_truth_table<NumVars, true>& second, Fn&& op )
{
  auto result = first.construct();
  result._bits = op( first._bits, second._bits );
  result.mask_bits();
  return result;
}
/*! \endcond */

/*! \brief Perform bitwise ternary operation on three truth tables

  The dimensions of `first`, `second`, and `third` must match.  This
  is ensured at compile-time for static truth tables, but at run-time
  for dynamic truth tables.

  \param first First truth table
  \param second Second truth table
  \param third Third truth table
  \param op Ternary operation that takes as input two words (`uint64_t`) and returns a word

  \return new constructed truth table of same type and dimensions
 */
template<typename TT, typename Fn>
auto ternary_operation( const TT& first, const TT& second, const TT& third, Fn&& op )
{
  assert( first.num_vars() == second.num_vars() && second.num_vars() == third.num_vars() );

  auto result = first.construct();
  auto it1 = first.cbegin();
  const auto it1_e = first.cend();
  auto it2 = second.cbegin();
  auto it3 = third.cbegin();
  auto it = result.begin();

  while ( it1 != it1_e )
  {
    *it++ = op( *it1++, *it2++, *it3++ );
  }

  result.mask_bits();
  return result;
}

/*! \cond PRIVATE */
template<int NumVars, typename Fn>
auto ternary_operation( const static_truth_table<NumVars, true>& first, const static_truth_table<NumVars, true>& second, const static_truth_table<NumVars, true>& third, Fn&& op )
{
  auto result = first.construct();
  result._bits = op( first._bits, second._bits, third._bits );
  result.mask_bits();
  return result;
}
/*! \endcond */

/*! \brief Computes a predicate based on two truth tables

  The dimensions of `first` and `second` must match.  This is ensured
  at compile-time for static truth tables, but at run-time for dynamic
  truth tables.

  \param first First truth table
  \param second Second truth table
  \param op Binary operation that takes as input two words (`uint64_t`) and returns a Boolean

  \return true or false based on the predicate
 */
template<typename TT, typename Fn>
bool binary_predicate( const TT& first, const TT& second, Fn&& op )
{
  assert( first.num_vars() == second.num_vars() );

  return std::equal( first.begin(), first.end(), second.begin(), op );
}

/*! \cond PRIVATE */
template<int NumVars, typename Fn>
bool binary_predicate( const static_truth_table<NumVars, true>& first, const static_truth_table<NumVars, true>& second, Fn&& op )
{
  return op( first._bits, second._bits );
}
/*! \endcond */

/*! \brief Assign computed values to bits

  The functor `op` computes bits which are assigned to the bits of the
  truth table.

  \param tt Truth table
  \param op Unary operation that takes no input and returns a word (`uint64_t`)
*/
template<typename TT, typename Fn>
void assign_operation( TT& tt, Fn&& op )
{
  std::generate( tt.begin(), tt.end(), op );
  tt.mask_bits();
}

/*! \cond PRIVATE */
template<int NumVars, typename Fn>
void assign_operation( static_truth_table<NumVars, true>& tt, Fn&& op )
{
  tt._bits = op();
  tt.mask_bits();
}
/*! \endcond */

/*! \brief Iterates through each block of a truth table

 The functor `op` is called for every block of the truth table.

 \param tt Truth table
 \param op Unary operation that takes as input a word (`uint64_t`) and returns void
*/
template<typename TT, typename Fn>
void for_each_block( const TT& tt, Fn&& op )
{
  std::for_each( tt.cbegin(), tt.cend(), op );
}

/*! \brief Iterates through each block of a truth table in reverse
    order

 The functor `op` is called for every block of the truth table in
 reverse order.

 \param tt Truth table
 \param op Unary operation that takes as input a word (`uint64_t`) and returns void
*/
template<typename TT, typename Fn>
void for_each_block_reversed( const TT& tt, Fn&& op )
{
  std::for_each( tt.crbegin(), tt.crend(), op );
}

/*! \cond PRIVATE */
template<typename TT, typename Fn>
void for_each_one_bit_naive( const TT& tt, Fn&& op )
{
  for ( uint64_t bit = 0u; bit < tt.num_bits(); ++bit )
  {
    if ( get_bit( tt, bit ) )
    {
      op( bit );
    }
  }
}
/*! \endcond */

/*! \cond PRIVATE */
template<typename TT, typename Fn>
void for_each_one_bit_jump( const TT& tt, Fn&& op )
{
  uint64_t offset = 0, low_bit, value;

  for ( auto block : tt._bits )
  {
    while ( block )
    {
      low_bit = value = block - ( block & ( block - 1 ) );

      value |= value >> 1;
      value |= value >> 2;
      value |= value >> 4;
      value |= value >> 8;
      value |= value >> 16;
      value |= value >> 32;
      op( offset + detail::de_bruijn64[( static_cast<uint64_t>( ( value - ( value >> 1 ) ) * UINT64_C( 0x07EDD5E59A4E28C2 ) ) ) >> 58] );

      block ^= low_bit;
    }
    offset += 64;
  }
}

template<int NumVars, typename Fn>
void for_each_one_bit_jump( const static_truth_table<NumVars, true>& tt, Fn&& op )
{
  uint64_t block = tt._bits;

  while ( block )
  {
    uint64_t low_bit = block - ( block & ( block - 1 ) );
    uint64_t value = low_bit;

    value |= value >> 1;
    value |= value >> 2;
    value |= value >> 4;
    value |= value >> 8;
    value |= value >> 16;
    value |= value >> 32;
    op( detail::de_bruijn64[( static_cast<uint64_t>( ( value - ( value >> 1 ) ) * UINT64_C( 0x07EDD5E59A4E28C2 ) ) ) >> 58] );

    block ^= low_bit;
  }
}
/*! \endcond */

/*! \brief Iterates through each 1-bit in the truth table

  The functor `op` is called for every bit position of the truth table
  for which the bit is assigned 1.

  \param tt Truth table
  \param op Unary operation that takes as input a word (`uint64_t`) and returns void
*/
template<typename TT, typename Fn>
inline void for_each_one_bit( const TT& tt, Fn&& op )
{
  for_each_one_bit_naive( tt, op );
}
} /* namespace kitty */
